Insulating glass units excellent in heat insulating properties have been recently attracting attention in the fields of construction and production of vehicles such as automobiles for the purpose of, for example, maintaining the temperature inside a room, a car, or the like.
FIG. 5 is a schematic sectional view showing an example of the constitution of such a (conventional) insulating glass unit.
A conventional insulating glass unit 50 shown in FIG. 5 generally has a structure in which at least two glass plates 1 are opposed to each other through a metal spacer 7 made of aluminum or the like; a hollow layer (air layer) 2 is formed between the glass plates 1; a primary seal (adhesive layer) 4 is interposed between the spacer 7 and each of the glass plates 1 to shield the air layer 2 from outside air; and a secondary seal (sealant) 5 such as a two-component, room-temperature curing type sealant typified by polysulfide or silicone sealant or butyl rubber hot melt is placed in an end gap surrounded by the spacer 7, the primary seals 4, and the opposing glass plates 1.
A method adopted for producing the insulating glass unit involves filling a hollow portion of the metal spacer (especially aluminum spacer) 7 having a hollow structure with a desiccant (moisture absorbent) 6 as the spacer to be used therefor; arranging the spacer 7 between the glass plates 1; adjusting the width between the glass plates 1 to a predetermined value; and casting the sealant 5. As described above, the production process is complicated, and an insulating glass unit using the room-temperature curing type sealant 5 involves a lot of time to cure the sealant, leading to incapability to ship it immediately after the production. In particular, in winter, the insulating glass unit must be placed in a heating chamber for curing the sealant. Accordingly, a technique for improving the productivity of insulating glass units through simplification of their production process and reduction of the curing time has been demanded.
For the purpose of satisfying the demand, an insulating glass unit using, as a spacer, a resin composition kneaded as required with a desiccant instead of the aluminum spacer has been proposed (see, for example, Patent Documents 1 to 3). An example of the resin composition includes a thermoplastic resin composition which contains a butyl rubber, a crystalline polyolefin, and an inorganic filler, and in which the ratio of the butyl rubber to the total of the butyl rubber and the crystalline polyolefin is 50 to 98 wt %; the ratio of the crystalline polyolefin to the total of the butyl rubber and the crystalline polyolefin is 2 to 50 wt %; and the ratio of the inorganic filler to 100 parts by weight of the total of the butyl rubber and the crystalline polyolefin is 200 parts by weight or less (see claim 6 of Patent Document 2).
There has also been proposed a thermoplastic elastomer composition which uses, as starting materials, a thermoplastic resin having a moisture vapor transmission rate of 100 g/(m2·24 h) or lower (30 μm in thickness) and a rubber having a moisture vapor transmission rate of 300 g/(m2·24 h) or lower (30 μm in thickness) when cross-linked; and which has, in a thermoplastic resin continuous phase, a disperse phase composed of a rubber composition at least part of which is dynamically cross-linked (see Patent Document 4).
Such thermoplastic resin composition and thermoplastic elastomer composition can be made into spacers and also serve as sealants. Therefore, an insulating glass unit which has a spacer and in which ends of opposing glass plates are sealed can be produced by casting the thermoplastic resin composition or thermoplastic elastomer composition at the ends of the opposing insulating glass members. Accordingly, the insulating glass unit production process using the thermoplastic resin composition or thermoplastic elastomer composition is easier than that using a metal spacer, so productivity can be improved to some extent.
Patent Document 1: JP 10-110072 A
Patent Document 2: JP 10-114551 A
Patent Document 3: JP 10-114552 A
Patent Document 4: JP 2000-119537 A